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Old 06-28-2013, 11:00 PM
DavGoodlin's Avatar
DavGoodlin DavGoodlin is offline
Motorola Minion
 
Join Date: Aug 2011
Location: near Strasburg PA
Posts: 3,501
After getting the output transformer in the mailbox yesterday, I had to try it first.
No improvement in volume, yet it measures 240 + 240 ohms on the primary - a huge change from the 2.8 K on the original.

Then i started examining the components between the 1st audio amp 7C6 and output tube grids and it did not exactly match the Riders 12 schemo....then I saw it - the "alternate audio circuit" on another page (12-64), showing a type 37 triode, a phase splitter for this model only.

When I first pulled the chassis for re-capping, I noticed an empty 5-pin tube socket, under the chassis, there were no filament wires on the socket. The tube chart pasted in the radio showed nothing in this position either. To confuse things further, an octal socket was installed by someone to use a 6X5 instead of the 84 rectifier tube.

Luckily, I had a Philco-branded 37 tube to plug in. Connecting the filament, then checking the resistors of this "found" phase splitter circuit, eased it up on the variac.

The volume is good nowbut 3 of the 6 speaker glue joints I had done without using construction paper, now sounded like a bee was in the speaker. After attending to the remaining speaker punctures like the first three, it should sound pretty good.
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